So a 2 week European vacationer is worth more to Disney than a 2 week US citizen? Why? Is there some type of advantage to Disney? If so, I don't see it.
1) Europeans vacation longer than US people - That's what happens when you have mandated vacation time (US doesn't)
2) Many Europeans face higher taxes than the US - making it advantageous to spend money in the US on goods and services
3) For many periods.. European's had favorable exchange rates.. making it advantageous to spend money in the US
4) The UK is the #2 economy in Europe
5) Northern Europe likes to vacation in the warmer climates
6) When you have long travel times.. you tend to make longer trips
7) The UK is very familiar with Disney's brand and products
All of these things make it very compelling for UK people to vacation in Florida and the Caribbean. By making Disney a very attraction, and highly discounted destination... Disney is very successful in luring those long vacation goers to make their holiday a Disney one.
Why is the US different? Well for one.. how many US workers have more than 5 weeks of vacation? (the minimum in the UK). As such, US folks have shorter trips. There is no point to lure them with 14+ tickets when most will take trips <10 days max. Second, US people have less travel, and less competitive options competing with Florida. Europeans can vacation in the Med and be much closer.. so it takes more to lure them to tip the scales in your favor.
The UK is a huge demographic for WDW. Disney invests heavily to ensure it gets those international spenders on grand vacations.
Really the biggest thing is these tourists are going to spend a lot of money on long vacations - Disney makes itself attractive to try to ensure those vacations are Disney ones.